Method of forming a semiconductor device including vertical contact fingers

Abstract

A method of forming a semiconductor device includes forming vertical contact fingers in a substrate having side portions that are flexible. Contact fingers are formed near one or more edges of the flexible side portions of the substrate. After semiconductor dies are mounted to and electrically coupled to the substrate, the semiconductor device may be encapsulated by placing the device in a mold chase including upper and lower mold plates. The lower mold plate is sized smaller than the substrate so that the flexible side portions of the substrate including the contact fingers fold vertically upward to fit within the mold.

We claim: 
     
       1. A method of forming a semiconductor device, comprising the steps of:
 mounting one or more semiconductor dies on a flexible substrate, the flexible substrate having a first length; 
 positioning the flexible substrate in a mold chase, the mold chase having a second length less than the first length, and the mold chase having a shape defined by a bottom surface and one or more side surfaces orthogonal to the bottom surface; 
 folding the flexible substrate against the bottom surface and side surfaces so that the mold chase changes a shape of the flexible substrate to conform the flexible substrate to the shape of the mold chase; 
 encapsulating the one or more semiconductor dies in a mold compound, and 
 wherein said step of positioning the flexible substrate in the mold chase, and folding the one or more sides of the flexible substrate comprises the step of folding the one or more sides upward about 90°. 
 
     
     
       2. The method of  claim 1 , wherein said step of encapsulating the one or more semiconductor dies comprises the step of adhering the one or more sides of the flexible substrate to a surface of the mold compound. 
     
     
       3. The method of  claim 1 , further comprising the step of forming one or more contact fingers in the one or more sides of the flexible substrate, on a side of the flexible substrate opposite a side on which the one or more semiconductor dies are mounted, prior to the encapsulating step. 
     
     
       4. The method of  claim 1 , wherein said step of positioning the flexible substrate in the mold chase, and folding the one or more sides of the flexible substrate comprises the step of folding two opposed sides upward. 
     
     
       5. The method of  claim 1 , wherein said step of mounting one or more semiconductor dies on the flexible substrate comprises the step of mounting a plurality of non-volatile memory dies on the substrate. 
     
     
       6. The method of  claim 1 , wherein said step of positioning the flexible substrate in the mold chase and folding the one or more sides of the flexible substrate comprises the steps of positioning the flexible substrate on a bottom mold plate, folding the one or more sides upward, and sealing the flexible substrate within the mold chase with a top mold plate mated to the bottom mold plate. 
     
     
       7. The method of  claim 1 , wherein said step of encapsulating the one or more semiconductor dies in the mold compound comprises encapsulating the one or more semiconductor dies by flow free thin (FFT) molding. 
     
     
       8. The method of  claim 3 , further comprising the step of electrically interconnecting the one or more contact fingers with the one or more semiconductor dies. 
     
     
       9. The method of  claim 4 , further comprising the step of forming one or more contact fingers in each of the two opposed sides of the flexible substrate, on a side of the flexible substrate opposite a side on which the one or more semiconductor dies are mounted, prior to the encapsulating step. 
     
     
       10. The method of  claim 5 , wherein said step of mounting one or more semiconductor dies on the flexible substrate comprises the step of mounting the one or more semiconductor dies on the substrate in an area spaced from the one or more sides that fold upward during the encapsulation step. 
     
     
       11. The method of  claim 6 , wherein said step of encapsulating the one or more semiconductor dies in the mold compound comprises injecting molten mold compound into a cavity formed by the top and bottom mold plates. 
     
     
       12. A method of forming a semiconductor device, comprising the steps of:
 forming a flexible substrate with one or more contact fingers formed on a first surface of the flexible substrate, in one or more edge portions of the flexible substrate; 
 mounting one or more semiconductor dies on a second surface of the flexible substrate opposite the first surface; 
 positioning the flexible substrate in a mold chase, the mold chase changing a shape of the flexible substrate by folding the one or more edge portions upward against sides of the mold chase so that the one or more edge portions of the flexible substrate conform conforming to a contour of the mold chase; 
 encapsulating the one or more semiconductor dies in mold compound, and 
 wherein said step of positioning the flexible substrate in the mold chase, and folding the one or more edge portions of the flexible substrate comprises the step of folding the one or more edge portions upward about 90°. 
 
     
     
       13. The method of  claim 12 , further comprising the step of electrically interconnecting the one or more contact fingers with the one or more semiconductor dies. 
     
     
       14. The method of  claim 12 , wherein said step of forming the flexible substrate with one or more contact fingers formed in one or more edge portions of the flexible substrate comprises the step of forming contact fingers in two opposed edge portions. 
     
     
       15. The method of  claim 12 , wherein said step of mounting one or more semiconductor dies on the flexible substrate comprises the step of mounting the one or more semiconductor dies on the substrate in an area spaced from the one or more edge portions that fold upward during the encapsulation step. 
     
     
       16. The method of  claim 12 , wherein said step of positioning the flexible substrate in the mold chase and folding the one or more edge portions of the flexible substrate comprises the steps of positioning the flexible substrate on a bottom mold plate, folding the one or more edge portions upward, and sealing the flexible substrate within the mold chase with a top mold plate mated to the bottom mold plate. 
     
     
       17. The method of  claim 14 , wherein said step of positioning the flexible substrate in the mold chase, and folding the one or more edge portions of the flexible substrate comprises the step of folding the two opposed edge portions upward. 
     
     
       18. A method of forming a semiconductor device, comprising the steps of:
 forming a flexible substrate with one or more contact fingers formed on a first surface of the flexible substrate, in one or more edge portions of the flexible substrate, the flexible substrate having a first length; 
 mounting one or more semiconductor dies on a second surface of the flexible substrate opposite the first surface; 
 positioning the flexible substrate in a mold chase, the mold chase comprising a bottom plate and a top plate, the bottom plate having a bottom surface and side walls orthogonal to the bottom surface, the bottom surface having a second length smaller than the first length, the side walls of the mold chase folding the one or more edge portions to change a shape of the flexible substrate to conform the one or more edge portions of the flexible substrate conforming to a shape of the bottom plate; 
 sealing the top plate against the bottom plate; 
 encapsulating the one or more semiconductor dies in mold compound, and 
 wherein said step of positioning the flexible substrate in the mold chase, and folding the one or more edge portions of the flexible substrate comprises the step of folding the one or more edge portions upward about 90°.